In recent years, there are proposed optical interconnecting methods, in which a plurality of optical fiber lines are used to connect between apparatus such as large computers or mass-storage information exchange systems. The basic method of the optical interconnecting is, as shown in FIG. 1, connecting between apparatus 701 and 702 using an optical fiber line 703 which is made of a plurality of optical fibers and transmitting optical signals in parallel. A part of FIG. 1 is shown in FIG. 2. An optical module 704 for parallel transmission in the apparatus 701 and an optical module 705 for parallel transmission in the apparatus 702 are connected each other through multifiber optical connectors 706 and optical fiber lines 703.
As the multifiber optical connector 706, for example, there is an optical fiber array having a structure which optical fibers are held by V-shaped grooves formed by etching silicon (hereinafter simply called Si), (Journal of Lightwave Technology Vol. Lt-3 No. 5, p.1159, issued in October, 1985). Further, there is an optical fiber array having a structure which optical fibers are put between two L-shaped magnets, which array is disclosed in Japanese Patent Laid-open No. 4-86802 (86802/1992) has been known.
However, the aligned optical fiber array with an LD array or a PD array is fixed by using solder bonding or a YAG laser, its heat is also transferred to the optical fiber array, which heats up the optical fiber array to 200.degree. C. or above. Consequently, the problems of distortion appearing in micro order depending on the state of assembly, degrade of the coupling part, gas generation from adhesive around the optical fiber array, degrade of characteristics due to dew, and others arise.
As shown in FIG. 3, in the optical module 704, a fiber ribbon 703a is continuously formed and the multifiber optical connector 706 is placed at one end of the fiber ribbon 703a, which is what is called a pigtail type. It is also known that the fiber ribbon 703a and the multifiber optical connector 706 are placed at both ends of a silica waveguide 707 (e.g., an optical branching filter, an optical multiplexer, or an optical switch), which is what is called a jumper type.
However, the parallel optical transmission module, especially the pigtail type is difficult to handle the ribbon part of the optical fiber ribbon in each manufacturing process. A coating part of the optical fiber ribbon is made of resin which is inferior in heat resistance and which is difficult to handle when the module is fixed with solder or cleaned. For the jumper type, there are also disadvantages that the ribbon part of the optical fiber ribbon is complicated to handle, and that if it is stored in an small area, bend radius of the optical fiber needs 30 mm or above, which makes a space for mounting larger.
On the other hand, as shown in FIGS. 1 and 2, in the case of optically coupling the parallel optical transmission module with the external apparatus, the parallel optical transmission module is coupled with the optical connector 706 which ties to the external apparatus through the fiber ribbon 703a and the multifiber optical connector 706, but in this coupling, since the coupling is made at one end of fiber which is wired from the substrate to outside, wiring is often distorted, and when not coupling, the connector at one side is hang down. Consequently, it is inconvenient to handle the fiber ribbon and the coupling end face of the fiber may be damaged.
It is an object of the present invention to provide an optical fiber array with sufficiently high airtightness and a method for the same. Another object of the present invention is to provide a parallel transmission module, a method for manufacturing the parallel transmission module, and housing structure.